Method for calibrating a fuel injection valve, and fuel injection valve

ABSTRACT

In known fuel injection valves, a perforated disk having metering openings is disposed downstream of the valve seat. Adjusting the static fuel quantity injected during the steady opening state of the fuel injection valve is accomplished by means of the precise manufacture of the metering openings. Despite the high expense and effort of manufacture, an undesirably high deviation in the static fuel quantity of the various fuel injection valves occurs in mass production. The static fuel quantity is adjusted directly at the completely assembled fuel injection valve, so that the deviation of the static fuel quantity of the various fuel injection valves is minimized. To this end, the valve housing and the perforated disk are moved relative to one another, and as a result the various free flow cross sections of the metering openings are varied until the injected fuel quantity flow match the required fuel quantity flow. The method according to the invention is suitable for fuel injection valves of various types.

BACKGROUND OF THE INVENTION

The invention is based on a method for adjusting the static fuelquantity injected during the steady opening state of a fuel injectionvalve, as generically defined hereinafter, as well as to a fuelinjection valve, as disclosed herein and known from German PatentDisclosure Document DE-OS 37 10 467. The fuel injection valve known fromDE-OS 37 10 467 has a perforated disk downstream of its valve seat. Theadjustment of the static fuel quantity is effected by the accuratemanufacture of the metering openings embodied in the perforated disk.Despite the high production investment, the deviation in the static fuelquantity of individual mass-produced fuel injection valves isundesirably pronounced. This creates the danger that a variably highfuel quantity will be delivered to the various cylinders of an internalcombustion engine.

OBJECT AND SUMMARY OF THE INVENTION

The method according to the invention for adjusting the static fuelquantity produced during the steady opening state of a fuel injectionvalve, and the fuel injection valve have the advantage over the priorart that the static fuel quantity is adjustable in a simple manner, inthe otherwise completely assembled fuel injection valve, by varying thefree flow cross sections of the metering openings. This makes itpossible to assure that the mass-produced fuel injection valves exhibitespecially slight deviation in the static fuel quantity, and that thesame fuel quantity will be metered to the various cylinders of aninternal combustion engine, for instance.

An improvement in fuel atomization is moreover attained by the partialcoverage of the metering openings.

Further advantageous features of and improvements to the method revealedas well as the fuel injection valve are possible with the provisionsrecited in the dependent claims.

Advantageously, the perforated disk in the valve housing can be rotatedrelative to one another in order to adjust the static fuel quantity.

For the especially simple, economical embodiment of a fuel injectionvalve serving to carry out the method of the invention, it isadvantageous if the flow opening, provided immediately upstream of theperforated disk, of the flow conduit of the fuel injection valve has across section that deviates from the circular shape, preferably being inthe form of an oblong slot or a rosette.

For the same reason, it is also advantageous if an intermediate disk isprovided axially immediately upstream of the perforated disk, that is,between the face end of the nozzle body and the perforated disk, theintermediate disk being supported in a manner fixed against rotation andfirmly joined to the nozzle body, with its at least one through openingcommunicating with both the flow opening of the flow conduit and themetering openings of the perforated disk.

It is especially advantageous if the intermediate disk has the samenumber of through openings as the perforated disk has metering openings,and if the metering openings of the perforated disk and the throughopenings of the intermediate disk have the same diameter and areembodied on the same hole circle diameter.

It is especially advantageous if the perforated disk and theintermediate disk are manufactured as identical parts, which hasadvantages not only in terms of simple and more economical manufacturebut also assembly. This embodiment of the perforated disk andintermediate disk is especially practical if the perforated disk and theintermediate disk are rotatable relative to one another for adjustingthe static fuel quantity by the method of the invention.

For the sake of embodying the metering openings of the perforated diskand the through openings of the intermediate disk with especially sharpedges, it is advantageous if the perforated disk and/or the intermediatedisk are made of monocrystalline silicon, resulting in especially goodfuel atomization.

DRAWING

Exemplary embodiments of the invention are shown in simplified form inthe drawing and described in further detail in the ensuing description.

FIG. 1 is a fragmentary view of a fuel injection valve serving to carryout the method of the invention;

FIG. 2 is a highly enlarged detail of FIG. 1;

FIG. 3 is a section through the fuel injection valve in accordance witha first exemplary embodiment, taken along the line III--III of FIG. 2;

FIG. 4 is a section through the fuel injection valve in accordance witha second exemplary embodiment, taken along the line IV--IV of FIG. 2;

FIG. 5 is a fragmentary view of a third exemplary embodiment of a fuelinjection valve for carrying out the method of the invention; and

FIG. 6 is a section taken along the line VI--VI of FIG. 5.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

In FIG. 1, an electromagnetically actuatable fuel injection valve, forexample, for fuel injection systems of mixture-compressing internalcombustion engines with externally supplied ignition, for example, isshown in which the static fuel quantity can be adjusted by the method ofthe invention.

The fuel injection valve has a tubular, for instance stepped valvehousing 1 made of a ferromagnetic material, in which a magnet coil 3 isdisposed on a coil body 2. By its lower housing end 4, the valve housing1 axially partially surrounds a nozzle body 5. A cylindrical, hollowarmature 8 cooperates with the magnet coil 3 and protrudes through amagnetic line conducting shoulder 9 of the valve housing 1 in the axialdirection. The armature 8 has a stepped longitudinal bore 10. Thearmature 8, by a region 12 remote from the magnet coil 3, peripherallyengages a retainer part 14 of a valve needle 15 and is firmly joined tothe valve needle 15.

The nozzle body 5 has a stepped, continuous flow conduit 19 that isconcentric with a longitudinal valve axis 16. On its end remote from thevalve housing 1, a conical valve seat face 20 is formed in the flowconduit 19, as shown by the highly enlarged detail of the fuel injectionvalve in FIG. 2. Two guide segments 22, for instance embodied assquares, of the valve needle 15, are guided by the guide region 21 ofthe flow conduit 19, but also leave an axial passageway free for thefuel.

A compression spring 24 rests by one end on a bearing shoulder 23 of thelongitudinal bore 10 of the armature 8, toward the magnet coil 3. By itsother end, the compression spring 24 is supported on a fixed adjustingbush, not shown. The compression spring 24 urges the armature 8 and thevalve needle 15 joined to it in the direction of the valve seat face 20.

With radial spacing, the valve needle 15 penetrates a through opening 26in a stop plate 27, which is disposed between a face end 28 of thenozzle body 5 toward the armature 8 and a retaining shoulder 29 embodiedin a flow bore 30 of the valve housing 1. In the stop plate 27, a recess31, the inside diameter of which is larger than the diameter of thevalve needle 15, is provided, leading from the through opening 26 to theperiphery of the stop plate 27.

Axially between the retaining part 14 and the guide segment 22 towardthe retaining part 14, the valve needle 15 has a stop flange 32. Thestop flange 32 of the valve needle 15 cooperates with the stop plate 27in such a way that the opening stroke of the valve needle 15 is limited.Remote from the retaining part 14, the valve needle 15 has a conicalsegment 33, acting as a valve closing part, which cooperates with theconical valve seat face 2 of the nozzle body 5 and effects the openingand closing of the fuel injection valve. A tang 36 of the valve needle15 adjoins the conical segment 33 in the flow direction.

Adjoining the conical valve seat face 20 in the direction remote fromthe armature 8, the flow conduit 19 continues within a flow segment 35,and it ends in a flow opening 39 at one face end 40 of the nozzle body5.

Instead of the circular cross section shown, the flow segment 35 mayalso have some other cross section, for instance oval, rectangular, orother.

A perforated disk 42 which is embodied as flat is disposed at the faceend 40 of the nozzle body 5. The perforated disk 42 has at least two andfor example four circular metering openings 43, which communicate withthe flow opening 39 of the flow conduit 19 and whose longitudinal axis44 have the same orientation as the longitudinal valve axis 16 or areinclined relative to it. All the metering openings 3 have the samediameter, by way of example, but it is also possible for the variousmetering openings 43 to have a variably large diameter, or to have ashape departing from the circular, for instance with an oval orrectangular or similar cross section. All four metering openings 43 areembodied on the same hole circle diameter 45, by way of example.

The fastening of the perforated disk 42 to the face end 40 of the nozzlebody 5 is assured by a preparation sleeve 50. In an outer region, theperforated disk 42 rests with a second face 54 remote from the valveseat face 20 on a bottom 52 of a coaxial blind bore 53 of thepreparation sleeve 50, and it is pressed by its first face 51, towardthe valve seat face 20, against the face end 40 of the nozzle body 5. Arim 56 of the perforated disk 42, for instance formed by deep drawing,peripherally engages part of a conical region 57 of the nozzle body 5,so that the perforated disk 42, clamped between the bottom 52 of thepreparation sleeve 50 and the face end 40 of the nozzle body 5, has noradial play and as a result is centered relative to the nozzle body 5.

The clamping of the perforated disk 42 between the nozzle body 5 and thepreparation sleeve 50 is achieved for instance by screwing thepreparation sleeve 50, with an internal thread 58, onto an externalthread 58 embodied on the circumference of the nozzle body 5. Apreparation bore 60 extends concentrically with the longitudinal valveaxis 16 in the bottom 52 of the preparation sleeve 50 and extends as faras the face end 61 of the preparation sleeve 509 remote from theinternal thread 58. The fuel is injected through the metering openings43 into the preparation bore 60 of the preparation sleeve 50.

However, it is also possible to fasten the perforated disk 42 directlyto the face end 40 of the nozzle body 5, for instance by welding.

FIG. 3 shows a section through a first exemplary embodiment of a fuelinjection valve, serving to carry out the method of the invention, takenalong the line III--III of FIG. 2. The flow opening 39 of the flowconduit 19 of the nozzle body 5, in the first exemplary embodiment, hasa rosette-like cross section which deviates from the circularcross-sectional shape. The hole circle diameter 45, on which themetering openings 43 of the perforated disk 42 are disposed, is selectedsuch that the metering openings 43 are partially covered by the face end40 of the nozzle body 5; as a result, the various metering openings 43are only partially covered by the rosette-shaped cross section of theflow opening 39 of the flow conduit 19, and a free flow cross section 46is formed at each of the metering openings 43 as a result of thiscoverage. The portion of the cross section of the metering opening 43covered by the face end 40 of the nozzle body 5 is shown in dashed linesin FIG. 3.

After the assembly of the fuel injection valve, in a first method stepof the method of invention for adjusting the static fuel quantityinjected during the steady opening state, the quantity of fuel outputper unit of time from the opened fuel injection valve is measured, forinstance by means of a measuring container 64 communicating with thepreparation bore 60 via a fuel line 63. If the actual quantity outputdoes not match the desired, specified set-point quantity of the fuel,then in a second method step according to the invention, the fuelinjection valve or the valve housing 1 and the perforated disk 42 aremoved relative to one another, thereby varying the free flow crosssections 46 of the various metering openings 43. If the actual quantityoutput matches the specified set-point quantity, then the perforateddisk 42, in a third method step of the invention, is fixed to the nozzlebody 4 or to the valve housing 1, for instance by means of thepreparation sleeve 50.

A particularly simple method for adjusting the static fuel quantity,which for example can be employed for the first exemplary embodimentshown, comprises rotating the fuel injection valve or valve housing 1and the perforated disk 42 relative to one another to vary the free flowcross sections 46 of the various metering openings 43. The coaxialposition of the perforated disk 42 between the bottom 52 of thepreparation sleeve 50 and the face end 40 of the nozzle body 5 continuesto be assured as a result.

FIG. 4 shows a section through a fuel injection valve, serving to carryout the method of the invention, according to a second exemplaryembodiment, taken along the line IV--IV of FIG. 2. Elements that are thesame and function the same are identified by substantially the samereference numerals as in FIGS. 1-3. The flow opening 39 of the flowconduit 19 of the nozzle body 5 has a cross section in the form of anoblong slot, departing from the circular cross-sectional shape. Theperforated disk 42, clamped and centered between the bottom 52 of thepreparation sleeve 50 and the face end 40 of the nozzle body 5, has byway of example four circular metering openings 3, all of them with thesame diameter. However, the metering openings 43 may also have somedifferent cross-sectional shape and different cross sections.

The hole circle diameter 45 on which the four metering openings 43 arefor instance disposed, is selected such that the various meteringopenings 43 are partially covered by the oblong-slot-like flow openings39 of the flow conduit 19. The portion of the cross section of eachmetering opening 43 that is covered by the face end 40 of the nozzlebody 5 is shown in dashed lines in FIG. 4.

In a first method step, first the fuel quantity output per unit of timeduring the steady opening state of the completely assembled, opened fuelinjection valve is measured. If the actual quantity of fuel output doesnot match the specified set-point quantity, then in a second method stepof the invention, the fuel injection valve or valve housing 1 and theperforated disk 42 are rotated relative to one another, for example, andthe free flow cross sections 46 of the various metering openings 43 arevaried thereby. If the actual quantity output matches the specifiedset-point quantity, then the perforated disk 42, in a third method stepaccording to the invention, is fixed to the nozzle body 4 or valvehousing 1, for instance by means of the preparation sleeve 50.

FIGS. 5 and 6 show a third exemplary embodiment of a fuel injectionvalve, shown in fragmentary form and serving to carry out the method ofthe invention. Elements that are the same and function the same areidentified substantially by the same reference numerals as in FIGS. 1-4.FIG. 6 shows a section taken along the line VI--VI of FIG. 5. Theperforated disk 42 and the intermediate disk 70 are shown in FIG. 5 in asection taken along the line V--V of FIG. 6.

An end section 68 of the valve needle 15 cooperating with the conicalvalve seat face 20 is embodied spherically, for example, and effects theopening and closing of the fuel injection valve. The flow conduit 19ends immediately at the downstream end of the conical valve seat face20, for example, in the flow opening 39 at the face end 40 of the nozzlebody 5.

A flat intermediate disk 70 is disposed with its upper face 71approximately coaxially with the face end 40 of the nozzle body 5, andit is firmly joined to the nozzle body 5, for instance by laser welding.By way of example, the intermediate disk 70 has four circular throughopenings 72. The four through openings 72 communicate with the flowopening 39 of the flow conduit 19, and for example all have the samediameter, and as can be seen from FIG. 6 are for instance all embodiedon the same hole circle diameter 75. The through openings 72 of theintermediate disk 70 may also have a cross section that departs from thecircular shape, for example an oval, rectangular or similar crosssection. Moreover, the intermediate disk 70 may have only a single flowopening 72, which has approximately the cross-sectional shapes and sizesof the flow openings 39, as has been described for the exemplaryembodiments of FIGS. 3 and 4 and shown in dot-dashed lines in FIG. 6,for example.

The flat perforated disk 42 rests with its first face 51 on a face end74 of the intermediate disk 70 remote from the nozzle body 5. Theperforated disk 42 has four circular metering openings 43, for example.All four metering openings 43 are for example formed on the same holecircle diameter 45 and for example have the same diameter. The throughopenings 72 of the intermediate disk 70 and the metering openings 43 ofthe perforated disk 42 are not covered in the radial direction by theflow opening 39 of the flow conduit 19, because both the hole circlediameter 45 of the perforated disk 42 and the hole circle diameter 75 ofthe intermediate disk 70 are smaller, by at least half the diameter ofthe metering openings 43 or through openings 72, as applicable, than thediameter of the flow opening 39, which for instance has a circular crosssection. The flow opening 72 or flow openings 72 of the intermediatedisk 70 at least partially covers the metering openings 43 of theperforated disk 42, forming free flow cross sections 46 at the meteringopenings 43 in the region of the coverage, so that the fuel, when thefuel injection valve is opened, flows along the valve seat face 20through the flow opening 39, the through opening 72 or through openings72, and the adjoining metering openings 43, to reach the preparationbore 60 of the preparation sleeve 50.

To reduce production costs and to simplify assembly, it is practical ifthe perforated disk 42 and the intermediate disk 70 are embodiedcompletely identically, or in other words if the metering openings 43and the through openings 72 are located on the same hole circle diameter45, 75, are spaced apart by the same distance from one another, and havethe same circular shape and the same diameter.

The perforated disk 42 is pressed against the intermediate disk 70, thelatter being firmly joined to the nozzle body 5, in that the bottom 52of the coaxial blind bore 53 of the preparation sleeve 50 engages theperforated disk 42 in an outer region, at its second face 54 remote fromthe intermediate disk 70. The centering of the perforated disk 42between the bottom 52 of the preparation sleeve 50 and the intermediatedisk 70 is attained by means of a centering shoulder 76, of circularshape, for example, embodied in the stepped blind bore 53. The centeringshoulder 76 at least partially radially surrounds the circularcircumference of the perforated disk 42 without play, so that theperforated disk 42 can be rotated only relative to the valve housing 1or to the intermediate plate 70 joined to the nozzle body 5. Theperforated disk 42 is clamped between the intermediate disk 70 and thepreparation sleeve 50, for instance in that the preparation sleeve 50 isscrewed by its internal thread 58 onto the external thread 59 formed onthe circumference of the nozzle body 5. Concentrically with thelongitudinal valve axis 16, the preparation bore 60 begins at the bottom52 of the preparation sleeve 50 and ends at the face end 61 of thepreparation sleeve 50 remote from the internal thread 58.

If the fuel quantity output during the steady opening state by thecompletely assembled, opened fuel injection valve, measured in a firstmethod step according to the invention, does not match the specifiedset-point quantity, then in a second method step according to theinvention, the perforated disk 42 and the valve housing 1 or nozzleholder 5 having the intermediate disk 70 are rotated relative to oneanother. As a result, the free flow cross sections 46 of the variousmetering openings 43, and thus the fuel quantity output, are varied. Thesize of the free flow cross sections 46 of the metering openings 43depends on the degree of coverage of the metering openings 43 of theperforated disk 42 by the flow opening 72 or flow openings 72 of theintermediate disk 70. If the actual quantity of fuel output matches thespecified set-point quantity, then in this position, in a third methodstep according to the invention, the perforated disk 42 is fixedrelative to the intermediate disk 70 or nozzle holder 5 or to the valvehousing 1.

The longitudinal axes 44, 73 of the metering openings 43 or flowopenings 72 may extend in the same direction as the longitudinal valveaxis 16, but it is also possible for the longitudinal axes 44 of themetering openings 43 and/or the longitudinal axes 73 of the throughopenings 72 extend on an incline to the longitudinal valve axis 16.

The partial coverage of the metering openings 43 by the face end 40 ofthe nozzle body 5 or by the face end 74 of the intermediate disk 70 alsoleads to an improvement in the atomization of the fuel.

The perforated disk 42 and/or the intermediate disk 70 may be made froma monocrystalline silicon, and the metering openings 43 or throughopenings 72 may be formed by isotropic or anisotropic etching. Thismakes it possible to achieve especially sharp edges of the meteringopenings 43 and through openings 72, which effect good fuel atomization.

The method according to the invention has the advantage that in anotherwise completely assembled fuel injection valve, the static fuelquantity injected during the steady opening state can be adjusteddirectly. As a result, not only is the deviation in the static fuelquantity of the various fuel injection valves minimized, but a reductionin production costs are simultaneously attained as well.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

We claim:
 1. A fuel injection valve comprising a valve housing (1), avalve closing part cooperating with a valve seat face located in a flowconduit (19), and a first perforated disk (42) disposed downstream ofthe valve seat face, said first perforated disk including at least twometering openings (43); said first perforated disk (42) adapted to abuta face end (40) that partially covers the metering openings (43), theface end (40) and the first perforated disk (42) are movable relative toone another, for adjustably varying the cross sections (46) of thevarious metering openings (43), and thereafter locked in a set position,and said face end (40) is a part of a nozzle body (5) and is interruptedby a non-circular flow opening (39) of the flow conduit (19).
 2. A fuelinjection valve as defined by claim 1, in which the face end (40) andthe first perforated disk (42) are rotatable relative to one another. 3.A fuel injection valve as defined by claim 2, which includes a secondperforated disk disposed between said face end (40) and said firstperforated disk said second perforated disk (70) includes at least onethrough opening (72) disposed in an axial direction between a flowopening (30) and the first perforated disk (42), the first perforateddisk (42) being adapted to abut a face end (74) of said secondperforated disk, so that the at least one through opening (72) partiallycovers the metering openings (43) in said first perforated disk (42),and said first perforated disk and the second perforated disk arerelatively rotatable, for varying a free flow cross sections (46) of themetering openings (43), relative to said at least one through openingand said first and second perforated disks are flexible in a prearrangedposition.
 4. A fuel injection valve as defined by claim 3, in which thesecond perforated disk comprises the same number of through openings asthe first perforated disk has metering openings and further that themetering openings (43) of the first perforated disk (42) and the throughopenings (72) of the second perforated disk (70) are circular, comprisethe same diameter, and are located on a same hole circle diameter 45,75).
 5. A fuel injection valve as defined by claim 3, in which each ofsaid first perforated disks comprise a monocrystalline silicon.
 6. Afuel injection valve as defined in claim 2, in which said firstperforated disk comprises a monocrystalline silicon.
 7. A fuel injectionvalve as defined in claim 1, in which the flow opening (39) of the flowconduit (19) comprises a cross section in the form of an oblong slot. 8.A fuel injection valve as defined in claim 7, in which said firstperforated disk comprises a monocrystalline silicon.
 9. A fuel injectionvalve as defined by claim 1, in which the flow opening (39) of the flowconduit (19) comprises a rosette-like cross section.
 10. A fuelinjection valve as defined in claim 9, in which said first perforateddisk comprises a monocrystalline silicon.
 11. A fuel injection valve asdefined by claim 1, which includes a second perforated disk disposedbetween said face end (40) and said first perforated disk said secondperforated disk (70) includes at least one through opening (72) disposedin an axial direction between a flow opening (39) and the second firstperforated disk (42), the first perforated disk (42) being adapted toabut a face end (74) of said second perforated disk, so that the atleast one through opening (72) partially covers the metering openings(43) in said first perforated disk (42), and said first perforated diskand the second perforated disk are relatively rotatable, for varying afree flow cross sections (46) of the metering openings (43), relative tosaid at least one through opening and said first second perforated disksare fixable in a pre-arranged position.
 12. A fuel injection valve asdefined by claim 11, in which the second perforated disk comprises thesame number of through openings as the first perforated disk hasmetering opening and further that the metering openings (43) of thefirst perforated disk (42) and the through openings (72) of the secondperforated disk (70) are circular, comprise the same diameter, and arelocated on a same hole circle diameter (45, 75).
 13. A fuel injectionvalve as defined by claim 11, in which each of said first perforateddisks comprise a monocrystalline silicon.
 14. A fuel injection valve asdefined in claim 1, in which said at least one through opening (72) insaid second perforated disk and said metering openings (43) in saidfirst perforated disk have the same diameters and have centers which areon a circle having a diameter (45), and said disk are held in place by apreparation sleeve (50) threaded onto said nozzle body (5).
 15. A fuelinjection valve as defined by claim 1, in which said first perforateddisk comprises a monocrystalline silicon.